Structure and bonding in binuclear metal carbonyls from the analysis of domain averaged Fermi holes. I. Fe2(CO)9 and Co2(CO)8

The nature of the bonding in the above carbonyls was studied using the analysis of domain averaged Fermi holes (DAFH). The results straightforwardly confirm the conclusions of earlier theoretical studies in which the existence of direct metal–metal bond, anticipated for the above carbonyls on the basis of 18‐electron rule, was questioned. In addition to indicating the lack of direct metal–metal bond, the DAFH analysis also allowed to characterize the nature of the electron pairs involved in the bonding of the bridging ligands. The analysis has shown that because the number of available electron pairs is not sufficient for the formation of ordinary localized 2c‐2e bonds between terminal M(CO)3 fragments and the bridging ligands, the bonding in both carbonyls exhibits typical features of electron deficiency and one bonding electron pair is effectively involved in multicenter 3c‐2e bonding. Because of the symmetry of the complexes the bridging ligands are not distinguishable and all M‐C‐M bridges have a partial 3c‐2e nature via resonance of the localized structures. © 2008 Wiley Periodicals, Inc. J Comput Chem, 2008

[1]  K. C. Mundim,et al.  Definition of a multicenter bond index , 1990 .

[2]  Ramon Carbó-Dorca,et al.  Chemical structures from the analysis of domain‐averaged Fermi holes: Multiple metalmetal bonding in transition metal compounds , 2003, J. Comput. Chem..

[3]  E. Wigner,et al.  On the Constitution of Metallic Sodium. II , 1933 .

[4]  Roald Hoffmann,et al.  Bonding capabilities of transition metal carbonyl fragments , 1975 .

[5]  J. Dewar,et al.  The Physical and Chemical Properties of Iron Carbonyl , 1905 .

[6]  T. Kar,et al.  Ab initio theoretical study of three-centre bonding on the basis of bond index , 2000 .

[7]  C. Mealli,et al.  Integration of electron density and molecular orbital techniques to reveal questionable bonds: the test case of the direct Fe-Fe bond in Fe2(CO)9. , 2007, Inorganic chemistry.

[8]  R. V. G. Ewens,et al.  64. The crystal structure of iron enneacarbonyl , 1939 .

[9]  K. Wade.  The structural significance of the number of skeletal bonding electron-pairs in carboranes, the higher boranes and borane anions, and various transition-metal carbonyl cluster compounds , 1971 .

[10]  D. Mingos.  Molecular-orbital studies on carbametallaboranes. Part 1. Icosahedral carbaplatinaborane polyhedra , 1977 .

[11]  C. Mealli,et al.  Effects of the bridging ligands on the molecular and electronic structure of Fe2(CO)9 derivatives , 2003 .

[12]  H. Schaefer,et al.  Unsaturated binuclear homoleptic metal carbonyls M2(CO)x (M = Fe, Co, Ni; x = 5, 6, 7, 8). Are multiple bonds between transition metals possible for these molecules? , 2001 .

[13]  I. Agranat,et al.  Overcrowded twisted bi-4H-cyclopenta[def]-phenanthren-4-ylidene versus bi-9H-fluorenylidene, syn pyramidalization , 1990 .

[14]  R. Ponec,et al.  Electron pairing and chemical bonds. On the accuracy of the electron pair model of chemical bond , 1997 .

[15]  R. Ponec.  Electron pairing and chemical bonds. Chemical structure, valences and structural similarities from the analysis of the Fermi holes , 1997 .

[16]  P. Hohenberg,et al.  Inhomogeneous Electron Gas , 1964 .

[17]  G. Frenking,et al.  Chemical Structures from the Analysis of Domain-Averaged Fermi Holes. The Nature of Ga−Ga Bonding in PhGaGaPh2- and (PhGaGaPh)Na2 , 2004 .

[18]  H. Jacobsen,et al.  Octacarbonyl Diiron. A Density Functional Study , 1996 .

[19]  T. Kar,et al.  Bonding in beryllium carbonyls , 1994 .

[20]  R. Bader.  Atoms in molecules : a quantum theory , 1990 .

[21]  W. Kohn,et al.  Self-Consistent Equations Including Exchange and Correlation Effects , 1965 .

[22]  C. Bauschlicher.  On the bonding in Fe2(CO)9 , 1986 .

[23]  Robert Ponec,et al.  Chemical structures from the analysis of domain‐averaged fermi holes. Nature of the MnMn bond in bis(pentacarbonylmanganese) , 2005, J. Comput. Chem..

[24]  C. Gatti,et al.  Source function description of metal-metal bonding in d-block organometallic compounds. , 2007, Faraday discussions.

[25]  J. Kendall.  Inorganic Chemistry , 1944, Nature.

[26]  F. Cotton,et al.  Basic Inorganic Chemistry , 1976 .

[27]  J. Lewis.  Metal-metal interaction in transition metal complexes , 1965 .

[28]  P. Coppens,et al.  Experimental charge density study of dicobalt octacarbonyl and comparison with theory , 1983 .

[29]  R. Ponec,et al.  Domain-averaged Fermi holes – a new means of visualization of chemical bonds. Bonding in hypervalent molecules , 2001 .

[30]  E. Baerends,et al.  Electronic structure of binuclear metal carbonyl complexes , 1980 .

[31]  R. King,et al.  Binuclear Homoleptic Iron Carbonyls: Incorporation of Formal Iron−Iron Single, Double, Triple, and Quadruple Bonds, Fe2(CO)x (x = 9, 8, 7, 6) , 2000 .

[32]  S. Alvarez,et al.  The [M2(CO)8] Complexes of the Cobalt Group , 2001 .

[33]  Robert Ponec,et al.  Investigation of Some Properties of Multicenter Bond Indices , 1997 .

[34]  W. Griffith,et al.  Vibrational spectra of metal–metal bonded complexes of group VIII , 1969 .

[35]  R. Ponec,et al.  Multicenter bonding in organic chemistry. Geometry-sensitive 3c-2e bonding in (C...H...C) fragments of organic cations. , 2004, The Journal of organic chemistry.

[36]  D. L. Cooper,et al.  Anatomy of bond formation. Bond length dependence of the extent of electron sharing in chemical bonds from the analysis of domain-averaged Fermi holes , 2007 .

[37]  R. Ponec,et al.  MULTICENTRE BOND INDICES FROM THE GENERALIZED POPULATION ANALYSIS OF HIGHER ORDER DENSITIES , 1996 .

[38]  L. E. Alexander,et al.  The crystal structure of dicobalt octacarbonyl , 1964 .

[39]  Roald Hoffmann,et al.  Building Bridges Between Inorganic and Organic Chemistry (Nobel Lecture) , 1982 .

[40]  T. Kar,et al.  Theoretical study of multi-centre bonding using a delocalised MO approach , 1992 .

[41]  R. Hoffmann.  Theoretical organometallic chemistry. , 1981, Science.

[42]  A. Sironi,et al.  Chemical bonding in transition metal carbonyl clusters: complementary analysis of theoretical and experimental electron densities , 2003 .

[43]  R. Hoffmann,et al.  Triple-decker sandwiches , 1976 .

[44]  Tapas Kar,et al.  Three-center bond index , 1990 .

[45]  J. Cioslowski.  Isopycnic orbital transformations and localization of natural orbitals , 1990 .

[46]  Electron pairing and chemical bonds: Bonding in hypervalent molecules from analysis of Fermi holes , 1999 .

[47]  N. N. Greenwood,et al.  Mössbauer spectra, structure, and bonding in iron carbonyl derivatives , 1969 .

[48]  G. Frenking,et al.  Topological analysis of electron density distribution taken from a pseudopotential calculation , 1997, J. Comput. Chem..

[49]  P. S. Braterman.  Spectra and bonding in metal carbonyls, Part A: Bonding , 1972 .

[50]  F. Escudero,et al.  Atoms in molecules , 1982 .

[51]  H. Schaefer,et al.  Molecular Structures and Vibrational Frequencies of Iron Carbonyls: Fe(CO)5, Fe2(CO)9, and Fe3(CO)12 , 1998 .

[52]  F. Cotton,et al.  Accurate determination of a classic structure in the metal carbonyl field: nonacarbonyldi-iron , 1974 .

[53]  D. Mingos.  Recent Developments in Theoretical Organometallic Chemistry , 1977 .

[54]  J. Poblet,et al.  Laplacian of charge density for binuclear complexes : terminal vs bridging carbonyls , 1993 .

[55]  Zhenyang Lin,et al.  Stereochemistry of Seven-Coordinate Main Group and d0 Transition Metal Molecules , 1996 .

[56]  R. Ponec.  Electron pairing and chemical bonds. Molecular structure from the analysis of pair densities and related quantities , 1998 .

[57]  R. Hoffmann,et al.  Cp2M2(CO)4 - quadruply bridging, doubly bridging, semibridging, or nonbridging? , 1980 .

[58]  S. Alvarez,et al.  Theoretical Study of Bonding, Structure, and Vibrational Spectra of the [Fe2(CO)8]2- Anion and Its Derivatives† , 2001 .

[59]  J. Poblet,et al.  Multiple metal additions to C{sub 60}. An ab initio study of [M(PH{sub 3}){sub 2}]{sub n}C{sub 60} (M = Pt and Pd; n = 1, 2, and 6) , 1995 .

[60]  J. Reinhold,et al.  Orbital contributions to the molecular charge and energy density distributions in Co2(CO)8. , 2005, Inorganic Chemistry.

[61]  N. N. Greenwood,et al.  Structural studies of the carbonylate and carbonyl hydride anions of iron , 1969 .

[62]  Multicenter bonding and the structure of electron-rich molecules. Model of three-center four-electron bonding reconsidered , 2004 .